(sān'tə ān'ə) A strong, dry, hot wind that blows from the desert regions of southern California toward the Pacific coast, usually in winter. The Santa Ana wind occurs when a region of high pressure forms over the Great Basin (the high plateau east of the Sierra mountains and west of the Rocky mountains). The clockwise rotation of air around this high-pressure region forces air down from the plateau. As it descends, the air warms up and picks up speed. Because the wind is hot and dry, it contributes to the hazardous fire conditions of southern California.